Decoupling body shape and mass distribution in birds and their dinosaurian ancestors.

Macaulay, Sophie, Hoehfurtner, Tatjana, Cross, Samuel RR ORCID: 0000-0002-3096-3428, Marek, Ryan D, Hutchinson, John R ORCID: 0000-0002-6767-7038, Schachner, Emma R, Maher, Alice E ORCID: 0000-0001-7544-3947 and Bates, Karl T ORCID: 0000-0002-0048-141X
(2023) Decoupling body shape and mass distribution in birds and their dinosaurian ancestors. Nature communications, 14 (1). 1575-.

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It is accepted that non-avian theropod dinosaurs, with their long muscular tails and small forelimbs, had a centre-of-mass close to the hip, while extant birds, with their reduced tails and enlarged wings have their mass centred more cranially. Transition between these states is considered crucial to two key innovations in the avian locomotor system: crouched bipedalism and powered flight. Here we use image-based models to challenge this dichotomy. Rather than a phylogenetic distinction between 'dinosaurian' and 'avian' conditions, we find terrestrial versus volant taxa occupy distinct regions of centre-of-mass morphospace consistent with the disparate demands of terrestrial bipedalism and flight. We track this decoupled evolution of body shape and mass distribution through bird evolution, including the origin of centre-of-mass positions more advantageous for flight and major reversions coincident with terrestriality. We recover modularity in the evolution of limb proportions and centre-of-mass that suggests fully crouched bipedalism evolved after powered flight.

Item Type: Article
Uncontrolled Keywords: Animals, Birds, Dinosaurs, Somatotypes, Phylogeny, Fossils, Biological Evolution
Divisions: Faculty of Health and Life Sciences
Faculty of Health and Life Sciences > Institute of Life Courses and Medical Sciences
Depositing User: Symplectic Admin
Date Deposited: 14 Mar 2023 10:14
Last Modified: 29 Apr 2023 00:54
DOI: 10.1038/s41467-023-37317-y
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